Railway track circuit apparatus



Jan. 23, 1945. P. N. MARTlN 2,367,729

I RAILWAY TRACK CIRCUIT APPARATUS Filed OCC. 29, 1941 .D I, 41"?,v Z f 'F2 4 f J; Y 6 Fl' J. 5-"^" 5/11 y ILL?M 7"] A L I a .fv-/ .5' O Sfr/' Q V ,7 15* mi v 1 2- .1 i? 15/ Ll (9' n I0. F 9 9 C'ozzzpol Q 7H? Canllaozff F TPH Il Lf j? 15 M J5 FZ' .la Fl' .1b. l g E I0 Conf/10( Conzlaczr Hm Tray/VEP'.

Patented Jan. 23, 1945 RAILWAY' TRACK CIRCUIT APPARATUS Paul N. Martin,r Penn Township, Allegheny a County, Pa.,.assignor to The Union Switch-& Signal Company, Swissvale, Pa., a corporation of Pennsylvania l Application -October 29, 1941, Serial No. 416,950 =="(Cl. 246-28) 6 Claims.

My invention relates'to 'railway track circuit apparatus, and it has particular reference to the organization of such apparatus into railway track circuits arranged to be highlyfsensitive to train shunts and involving a track relay and means controlled thereby for conditioning the track relay to be energized at one level or. another according as the relay is picked upv or released, respectively.

An object of my invention is the provision -of ence` characters havebeen lemployedfto designate corresponding parts.U

Referring to the drawing, the reference chars acters l and la designate the track rails-of a` stretch of railway track divided, by the usual"- Y insulated joints 2 into a track, sectionD-E. A

novel and improved meansior improving .thek

shunting sensitivity of track circuits.

Another object is. the provision of track ,cir-

cuitsarranged to cause the track relay'to be energized at either a pick-up or a holdinglevel:

andincorporating means .for shifting the track relay to its holding level immediately when the relay-picks up..

A further object is the provision of means in a track circuit to avoid false operation of gov-r erned apparatus caused Yby a high resistancestrain shunt 4,or by intermittent losses vof trainV4 shunt while a train occupies a track section.-

An additional object is the provision of track circuits .arranged to utilize -onlya minimum of energy derived' from' the track circuit andfinv corporating another source vof--energy for assistingf'in creatingvin the track relay its pick-up energylevel. 'Y

The above-mentioned and other importantY objectsrand characteristic features which willbecome`readily apparent fromy the following de` scription, are attained in accordance with my inventionby'utilizing a'repeater relay 'of a track Y relayfor controlling 'the usual functions con- In the accompanying drawing, Fig. 1 is a dia-y grammatic View illustrating one form of apparatus embodying my invention. Figs. la. and lb are .diagrammatic views representing. modiiications-.of a portionfof the apparatus krepresented in Fig..1. Fig. :2 is a diagrammatic 'view showing anotherlmodication'of the apparatus shown in Fig.1. In each of the-several views, similarx refersuitable source of current, such as a battery .3,

is connected through the usual current limiting resistor '4 across the rails I and la at one end D of the section, and a track relay, designated vby 1 v,

the reference character TR, has its winding vconnected to the rails at the opposite' end E of ithe section. The winding of relay TR comprises, as

shown, two coilsu 5 and Ei and the track circuit@l normally includescoil 5, resistor 1 and a portion of coil 6 of relay TR. The parts are so proportioned that under the assumed.norrnalcondi-.V

tions, relay TR is held energized at alevel only,r slightly above its release level. This energy level normally present in relay TR I shall termthe` holding level of relay TR.

Associated with relay TR is a repeater. or secondary relay TPR normally energized, as

shown, over an obvious circuit including front, contact 8 of relay TR and a suitable sourceoh current, such as a battery 9. RelayTPR is slow, to pick up and controlscontacts H! and! l which l.: may be used, as indicated, to govern functions, such as signals, locks, etc. usually controlled. yby

track circuit apparatus.

Relays TR and TPR cooperate incontrolling ,i

the energy level created in the relay in the following manner: When relay TR is released as when a train enters sectionD-E and shunts the relay, relay `TPR also is releasedfand an obvious '.vf circuit path comprising'back contact l2 of relay,L

TR and back contact I3 of relay TIRy is com.

pleted. This circuit path shunts resistorl and@y connects the lower terminal, as viewed-in the drawings, of coil 5 to the lower terminal I,of f, coil 6, ythereby interposing vadditional-coil turnsl 1Y` of the winding of relay TR in the track circuiti-w.. Under the assumed conditions, when'the shuntA is removed from relay TR, energy from the track` L.. rails energizes both the added coil turns and the coil turns normally in the track circuityandthe j, parts are so proportioned as to `cause an energyy: level above vthe pick-up energy level to be created-rf. in the relay. This energy level is suicientlyhighg;

to impart appreciable velocity to the armature structure before contact l2 opens sothat the ino,-v mentum of the armature together with the holds, .z y

ing energy level in the relay windings `will-'be sufcient to carry the armature up to itspicked-M4 up positionwhereit rwill be held byl. the holdingx-w energy in the winding. Relay TR is thus caused to operate its armature abruptly to its picked-up position, whereupon back contact I2 immediately opens to shift relay TR from its pick-up to its hold-up level.

The apparatus just described is characterized by the fact that the pick-up circuit of relay TR includes its own back contact I2, hence when the relay picks up it is shifted immediately to its hold-up circuit. This arrangement has a marked advantage over the usual primary-secondary relay combinations wherein the pick-up circuit of the track relay is controlled over a contact of the secondary relay but not by a contact of the track relay itself. Thus, with the usual primary-secondary relay combinations, in the event that a high resistance shunt condition exists in an occupied section, the shunt resistance might be sutllciently high to be ineifective to prevent pickup of the track relay when the relay is in its pickup circuit. The track relay accordingly might pick up, and be held up at its pick-up level until the secondary relay operates not only to shift the track relay to its holding level, but also to interrupt the control established by the contacts of the secondary relay over the functions governed thereby. After operation of the secondary relay has shifted the track relay to its lower energy level, the track relay will release in response to the high resistance shunt, and when the secondary relay releases to again condition the track relay to create its higher energy level. the track relay might again pick up and hold up until the secondary relay again operates. In such an arrangement, it is thus possible to have both the track and secondary relays pump, that is, alternately pick up and release, due to poor shunting conditions in a section of occupied track.

Apparatus arranged in accordance with my invention to incorporate a back contact of the track relay in its pick-up circuit functions in such manner that if relay TR is caused to pick up due to a high resistance shunt existing in an occupied section, the immediate transfer of the relay to its holding circuit will cause the relay to release immediately due to the high resistance shunt applied thereto. Should the high resistance shunt persist, relay TR might pumpf that is, pick up and release intermittently as long as the poor shunting conditions exist, but due to the relatively short intervals that relay TR closes its front contact 8 and the slow pick-up characteristics of relay TPR, relay TPR remains in its released position to maintain the proper control of its contacts and functions controlled thereby. When, however, the shunt is removed from the relay as by the train vacating the circuit, then relay TR. picks up and is shifted to its holding circuit where it remains. Relay TPR accordingly picks up at the end of its slow pick-up interval and the apparatus is restored to its normal condition. It follows, therefore, that the apparatus arranged in accordance with my invention provides a novel and improved arrangement whereby a track relay is conditioned to be energized at one level when it is picked up, is conditioned to be energized at a higher level when it is released, and controls its own energy level in such manner as to avoid causing operation of the associated secondary or control relay in the event that high resistance or poor shunting conditionsexist in the section.

The control of the energy level in relay TR, as represented in Fig. 1, is attained by shunting out a resistor and by simultaneously interposing coll turns in the track circuit. Either feature may, however, be individually employed to control the energy level in the relay. For example, resistor I may be connected, as shown in Fig. la, between the lower terminals of coils 5 and E, for limiting the current in these coils to a value such as to cause the lower or holding energy level to be created in the relay. Resistor I is shunted over the circuit path comprising back contacts I2 and I3 of relays TR and TPR, respectively, and when the resistor is shunted the current value in the relay may be increased to cause the higher or pick-up energy level to be created in the relay. In like fashion, coils 5 and E may be normally energized, as shown in Fig. 1b, at a value such that the holding level is created in relay TR, and when back contacts I 2 and I3 of relays TR and TPR are closed, an additional coil I5 may be connected in the track circuit for creating an additional energization, when the train shunt is removed from relay TR, sufficient to raise the energy level in the relay to its pick-up value.

In a further modification, represented in Fig. 2, coils 5 and 6 of relay TR are energized from source 3 over the track rails at a level sufficient to create in the relay its holding energy level, and when back contacts I2 and I3 are closed, coil I5 is energized from a local source, such as a battery 9, at a level just below the pick-up level of the relay. Thus, when section D-lL1 is occupied and relay TR is shunted, coil I5 is energized and maintains in the relay an energy level insufficient to pick up the relay, but sufficient when the shunt is removed and coils 5 and 6 become energized, to cooperate with the coils 5 and 6 in creating an energy level higher than the pick-up level of the relay. Relay TR of Fig. 2 accordingly will pick up when the shunt is removed from its windings 5 and 6, and when the relay picks up, its back contact I2 opens to place coil I5 on open circuit, thereby causing the energy level in the relay to be reduced to its holding level.

The arrangement represented in Fig. 2 incorporates back contact I2 of relay TR in its pickup circuit, hence relay TR might be picked up and released due to the existence of high resistance or poor shunting conditions in the section, without causing operation of relay TPR and its associated control contacts I0 and II. In addiition, the track circuit apparatus represented in Fig. 2 is arranged to derive from the track circuit only the energy'required to hold up the relay, and the additional energy required to raise the energization of the relay to its pick-up level is derived from a local source. This arrangement obviously enables the energization of the track circuit to be maintained at a minimum, thereby reducing the possibility of excessive ballast losses and enabling longer rail stretches to be incorporated into a track circuit.

Although I have herein shown and described only a few forms of railway track circuit apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims Withoutdeparting from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

l. In combination, a source of electrical potential, a first relay, a circuit connecting a portion of the winding of said first relay to said source for normally creating in said first relay an energy level above its release but below its pick-up level, a slow pick-up relay energized over a circuit including a front contact of said rst relay for exerting a'control dependent upon the position of said iirst relay, and a circuit including in series a back contact of said lirst relay and a back contact of said slow pick-up relay for connecting an additional portion of the winding of said iirst relay to said source, whereby to condition said iirst relay to create an energy level above its pick-up level.

2. In combination with a section of railway track provided with a source of current connected across the track rails at one end of the section, a track relay having a portion of its winding connected in circuit with a resistor across the track rails at the opposite end of said section for creating in said relay an energy level above its release but below its pick-up value, a slow pick-up control relay provided with an energizing circuit including a source of current and a front contact of said track relay, and a circuit including in series a back contact of said track relay and a back contact of said slow pickup control relay and an additional portion of said relay winding, for shunting said resistor by a circuit path which connects said additional portion of said relay winding across the track rails, whereby to condition said track relay to.

create an energy level above its pick-up level.

3. In combination with a section of railway track provided with a source of current connected across the track rails, a track relay having a portion of its winding connected across the track rails for creating an energy level above the release but below the pick-up level of the track relay, a slow pick-up controlrelay energized over a control circuit including a source of current and a front contact of said track relay, and a circuit including in series a back contact of said track relay and a back contact of said slow pick-up control relay for connecting said portion of the winding of said track relay and an additional portion of the winding of said track relay across the track rails, whereby to condition said track relay to create an energy level above its pick-up level.

4. In combination with a section of railway track provided with a source of current connected across the track rails, a track relay having its winding connected in circuit with a resistor across said track rails for creating in said track relay an energy level above its release but below its pick-up value, a slow pick-up control relay 5 energized over a circuit including a source of current and a front contact of said track relay, and a circuit including in series a back contact of said track relay and a back contact of said slow pick-up control relay for shunting said resistor, whereby to condition said track relay to create its pick-up energy level.

5. In combination `with a section of railway track provided with a source of current connected across the track rails, a track relay having a portion of its winding connected across said track rails for creating in said track relay an energy level intermediate the release and pick-up values of the track relay, a Slow pickup control relay provided with an energizing circuit including a source of current and a front contact of said track relay, and a circuit including in series a back contact of said track relay and a back contact of said slow pick-up control relay for energizing an additional portion of the winding of said relay with energy from a source of current, said two portions of the winding of said track relay being arranged to create additive fluxes whereby to condition said relay to create an energy level sufficient to cause said track relay to pick up.

6. In combination, a section of railway track having a source of current and the winding of a track relay connected across the rails at opposite ends of said section respectively, said winding energizing said relay at a level intermediate its pick-up and release levels, a slow .pick-up control relay energized over a circuit including a front contact of said track relay, an additional winding for said track relay, an

4o additional source of current, and a circuit in- .cluding a back contact of said track relay and a back contact of said slow pick-up control relay for connecting said additional source to said additional winding, said two windings being arranged to create additive fluxes when energized, whereby to condition said track relay to create an energy level having a value exceeding its pick-up level.

PAUL N. MARTIN. 

